Incipia blog

Apple Search Ads Study: Impact of Bid Changes

Gabe Kwakyi | January 24, 2017

In this study, we analyzed 50 different keyword bid changes from our Apple Search Ads campaigns to see how effective a lever adjusting bid was for influencing impression volume, as well as what the outcome on CPT and CPA was.

We studied:

  • 18 bid reductions and 32 bid increases
  • The bid changes ranged from -95% to +300%
  • All adjusted bids but one fell within $1 and $10
  • All keywords had at least 1 impression going into the test
  • All keywords but one had at least 2 taps going into the test
  • All keywords were exact match

Main Conclusions

  • Raising bid only caused impression volume to rise in 69% of events, yet in bid reductions, impressions were reduced in 83% of events.
    • This indicates that adjusting bids is not sufficient for raising impression volume, and other tactics are required to effectively grow impression volume.
  • The magnitude of the change of bid was not accurate at predicting the magnitude of the change in impression volume, CPT or CPA, and wild swings in metrics often occurred from changing a keyword's bid.
    • That is to say, reducing a keyword's bid by -25% did not mean that the keyword's impression volume, CPT and CPA would also be reduced by -25%; however, this is not necessarily surprising, given the nature of a PPC auction, where a change in bid even as small as $.01 could have a significant impact on how many auctions a keyword is entered into or wins.
  • Save a few outliers, the gradually larger the bid change, the gradually larger the change in impression volume. The same was mostly true for CPT, but not as true for CPA.
  • For keywords with larger impression volume, the bid changes did not seem to produce any improvement in accuracy of the expected outcome on impression volume, CPT or CPA.
  • The change in CPA for most keywords whose bids were increased was lower than the % of the bid change, and 25% of keywords saw a decline in CPA.

Study-Based Recommendations

  • Raising bid is still the most direct way to boost impression volume and, in the majority of cases did not lead to a change in CPA that was larger than the % of the bid change; however, there were many outliers where the bid change produced unexpected changes to impression volume, CPT and CPA. 
  • Even with exact match keywords, do not rely on bid changes as a reliable method to boost impression volume for performing keywords.
    • When raising bid, do so cautiously and re-assess the outcome afterward to determine whether the change was positive or negative, and adjust your decisions as appropriate.
  • Other options available for raising impression volume include:
    • Always opt to raise budget before raising bids.
    • Expand to other keywords that may also perform. There are always new keywords to discover! Use search and broad match as your discovery tools.
    • Try testing new app store description copy or a new icon or screenshots to get more taps out of the impressions you currently receive.
    • Add all search terms as either: exact match keywords if you desire traffic from them or negative keywords if they are undesirable. The goal is to use as few search terms matching to broad/search match as possible.
  • To make bid changes more reliable, narrow the dimensions you are targeting (i.e. time of day, day of week, device, geographic location, gender, age), to reduce variation in the audience whose keyword searches are being targeted.
  • If you are changing bids manually in the UI, make sure to double check that the bid actually saved. About half of the time our new bid amount would not save and we had to re-enter the bid multiple times before it would actually save.

More Data

  • Reducing/increasing bid proved significantly unreliable for producing an expected change in impression volume, CPT and CPA.
    • 74% of bid changes produced a matching direction of impression volume change (i.e. a bid reduction producing a corresponding reduction in impression volume).
      • Bid reductions matched at a rate of 83% to expected impression reductions, while bid increases matched at only 69% accuracy with impression increases.
    • 70% of bid changes produced a matching direction of CPT change (i.e. a bid increase producing a corresponding increase in CPT).
      • Bid reduction matched at 72% to expected CPT reductions, while bid increases matched at 69% accuracy with CPT increases.
    • 70% of bid changes produced a matching direction of CPA change (i.e. a bid increase producing a corresponding increase in CPA).
      • Bid reduction matched at 89% to expected CPA reductions, while bid increases matched at 59% accuracy with CPA increases.
  • 16% of keywords which saw bid increases stopped converting week over week and 19% of bid increased keywords saw their CPA rise more than 100% above the bid change %. Yet, 59% of keywords whose bids increased saw their CPA increase by an amount lower than the bid change %, and 28% of keywords with bid increases actually saw a decrease in CPA.
  • Eight keywords stopped serving impressions week over week; three of those had seen bid increases, and two of which saw reductions in impression volume.

average changes from bid increase vs reduction

You can view the dataset yourself here.

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Incipia is a mobile app development and marketing agency that builds and markets apps for companies, with a specialty in high-quality, stable app development and keyword-based marketing strategy, such as App Store Optimization and Apple Search Ads. For post topics, feedback or business inquiries please contact us, or send an inquiry to